IC-F3S-3 = Narrow Band (2.5 KHz modulation), 32 channels permanently divided in two 16 channel banks. This is the special model created for the US military for their soldier intercom. Initially the power was set low (0.1 - 0.5 watts out), but this proved inadequate for the military use in the field, and almost every radio I have seen has been previously re-set to 5W out, likely by the radio tech who initially programmed them. The programming software often includes the service software to do this.

The modulation width is set per radio (NOT per channel). It is possible to adjust the deviation via a pot on the radio board. This works fine for taking a narrow radio and using it on a wide system (for Rx and Tx). It will likely also work for taking a wide radio and using it on a narrow system. However, the conversion of the reciever includes swapping out several components, which is not really practical. So long as we are using narrow channels at wide channel spacing, we are good to go. Once the interstitial channels start being used, this will likely be unacceptable. The wide radio works OK recieving narrow, although the audio is a bit quieter.